Thermomagnetic Force for Small Spheroidal Particles '1'

The thermomagnetic force for small spheroidal particles is given in the Waldmann limit. In this limit the force is proportional to the surface area of the particle, and depends on the gas pressure p and on the magnetic field strength H only via H/p. For the gases HD, CH 4 , CO and N2 the ratio of the thermomagnetic and thermal forces is calculated from Senftleben-Beenakker effect data. It is pointed out that the sign and magnitude of the thermomagnetic force in the Waldmann limit give information on the relative sign of two non-diagonal collision cross sections. The dependence of the force on the orientations of the magnetic field and of the axis of the particle relative to the temperature gradient is discussed.